Ultrasound of the sentinel node in melanoma patients: echo-free island is a discriminatory morphologic feature for node positivity

Abstract

Unlike breast and thyroid cancer, the use of ultrasound (US)-guided fine needle aspiration cytology (FNAC) for preoperative staging is limited in melanoma. New US morphology criteria have shown that US-FNAC can correctly identify 50% of all involved sentinel nodes (SN) in melanoma patients before surgical excision. The aim of this study was to examine a new criterion: the echo-free island (EFI). A total of 1000 consecutively staged melanoma patients (Breslow thickness>1 or<1 mm, but ulcerated, Clark IV/V or regressed) scheduled for SN staging underwent preoperative US. US morphology items were assessed: peripheral perfusion, loss of central echoes, balloon shape, and EFI. FNAC was performed in case of suspicious and malignant US patterns. All patients proceeded to undergo an SN biopsy or direct completion lymph node dissection (CLND) (in the case of positive FNAC). In all, 57% of the patients were men. The mean/median Breslow thickness was 2.58/1.57 mm. The mean/median follow-up was 56/53 months. SN was positive in 21%. EFI information was available in 95.3%. EFI was seen in 40 patients (4%). EFI sensitivity was 10.8%, specificity was 97.6%, positive predictive value was 50%, and negative predictive value was 80.2%. EFI was significantly correlated to peripheral perfusion (67.5%). There was no correlation to balloon shape or loss of central echoes. Five-year melanoma-specific survival of patients with EFI was significantly worse: 80% versus 92% when absent. The EFI can be useful in the early detection of SN melanoma metastasis. It is an early sign of involvement and thus associated with a decreased survival.

Gamma probe and ultrasound guided fine needle aspiration cytology of the sentinel node (GULF) trial - overview of the literature, pilot and study protocol

“…Some of the studies mentioned in Table 1 are overlapping; the studies from Voit et al [29–33] concern the same database with more inclusions over time. In the studies that performed US prior to lymphoscintigraphy, sensitivity rates were low, ranging from 4.7% to 39%, and specificity rates were high, ranging from 86% to 100%.…”

Guidelines of care for the management of primary cutaneous melanoma

“…202,212 The use of nodal ultrasound is encouraged at baseline or follow-up in the setting of an equivocal LN on physical examination and for surveillance (1) when the patient meets the criteria for SLNB but does not undergo the procedure; (2) when SLNB is not possible or not technically successful (eg, because of failure of preoperative lymphoscintigraphic dye migration and inability to identify a draining SLN); and (3) when CLND is not performed in the setting of a positive SLNB. 2 Regional nodal ultrasound for melanoma detection requires specific radiologic expertise and understanding of established LN criteria, [237][238][239] and it has been less commonly used in the United States for this purpose. However, nodal ultrasound is less expensive, noninvasive, and safer than other imaging alternatives, and its use should be encouraged in the appropriate clinical setting and where radiologic expertise is available.…”

Top Advances in Dermatologic Ultrasound

“…The anechoic areas usually seen in the metastatic nodes are frequently due to compact nests of melanoma cells and not necrosis. 92,93 Ultrasound-guided fine needle cytology or biopsy can support the primary tumor diagnosis and its metastases, including the sentinel lymph node. 37,38,[94][95][96][97][98] Contrast-enhanced ultrasound has been reported to improve the detection of the sentinel lymph node in cutaneous melanoma.…”

“…The anechoic areas usually seen in the metastatic nodes are frequently due to compact nests of melanoma cells and not necrosis 92,93 …”